A great number of semi-automatic and fully automatic injection devices have been disclosed. Their construction is often very complex so that manufacturing costs are high. If after being used, a device is not intended for reuse but for disposal or recycling, then a device of this kind has to be composed of few parts and be very cheap to manufacture. Most injection devices which operate semi-automatically or fully automatically do not meet this demand. See for example the fully automatic injection devices according to DE 39 14 818-A1, DE 40 13 769-A1, or DE-UM 92 00 192 (all by Adamaszek). These devices require a first spring for the insertion of the needle and a second spring for the injection of the fluid, and furthermore, corresponding control devices that trigger the injection process by means of the second spring only when the insertion of the needle is finished, as a result of which these devices become very complex and expensive.
It is a task or objective of the invention to provide a new injection device.